Here's a breakdown of how to troubleshoot and potentially "repair" the leveling system:
1. Identify the Problem:
* What's not working? Are your headlights pointed too high, too low, or are they not adjusting at all? Is there a specific circumstance (like turning, hitting a bump) where the problem occurs? This helps narrow down the cause.
* Check the fuses: Make sure the fuses related to the headlamp leveling system are intact. Consult your owner's manual for the correct fuse locations and ratings.
* Visual Inspection: Look for any obvious damage to the wiring harness near the leveling sensor (usually located on the front suspension, often near the control arms). Look for broken wires, corrosion, or loose connectors.
2. Troubleshooting Steps:
* Check the Leveling Sensor: The sensor is a crucial part of the system. It's usually a potentiometer that measures the vehicle's ride height. Access to this sensor might require some disassembly, depending on its location.
* Clean the Sensor: Carefully clean the sensor contacts with electrical contact cleaner. This can sometimes resolve issues caused by dirt or corrosion.
* Test the Sensor (Advanced): This requires a multimeter to measure the resistance across the sensor's terminals as you manually adjust the vehicle's ride height. The resistance should change smoothly and predictably. If it doesn't, the sensor is likely faulty and needs replacement.
* Check the Wiring Harness: Inspect the entire wiring harness connecting the sensor to the control module (located somewhere in the vehicle's electrical system – you'll likely need a wiring diagram to locate this). Look for broken wires, loose connections, or corrosion. Repair any damaged wiring and secure loose connections.
* Check the Control Module (ECM/BCM): The control module receives the signal from the sensor and controls the headlamp leveling motors. A faulty control module is less common but possible. Testing this usually requires specialized diagnostic equipment.
3. Replacement (Most Likely Solution):
If your troubleshooting points to a faulty sensor, switch, or control module, replacement is typically the solution.
* Leveling Sensor: This is the most likely culprit and usually relatively inexpensive to replace. You'll need to locate a replacement part (possibly through a junkyard or auto parts store) and follow the appropriate instructions for its installation (often found in a repair manual).
* Leveling Switch (rarely the problem): Replacing the switch itself is typically not recommended unless all other causes are ruled out, and finding a replacement might be difficult.
* Control Module: Replacing the control module is generally expensive and should only be considered as a last resort after all other components are deemed functional.
Important Considerations:
* Repair Manual: A repair manual specific to your 2001 Pontiac Bonneville will be invaluable. It will provide detailed diagrams, component locations, and repair procedures.
* Wiring Diagram: This is crucial for tracing the wiring harness and identifying connections.
* Safety: Disconnect the battery's negative terminal before working on any electrical components.
In short: While you can't *repair* the leveling switch itself, you can fix the *problem* that's preventing the system from working. This usually involves replacing the leveling sensor or addressing wiring issues. Professional diagnosis is recommended if you're not comfortable working on your car's electrical system.
